Magnetic core assembly



March 27, 1962 L. T. LA PATKA ET AL 3,027,526

MAGNETIC CORE ASSEMBLY 2 Sheets-Sheet 1 Filed Dec. 23, 1957 INVENTORS A R E T. LA PATKA O MAYER j Wfi AGENT March 27, 1962 T. LA- PATKA ETI'AL 3,027,526

MAGNETIC CORE ASSEMBLY Filed Dec. 25, 1957 2 Sheets-Swat 2 LAWRENCE T. LA PATKA JACOB J'MAYER United States Patent Qffice 3,027,526 Patented Mar. 27, 1962 3,027,526 MAGNETIC CORE ASSEMBLY Lawrence T. La Patka, Collingswood, N.J., and Jacob J. Mayer, Ivyland, Pa., assignors to Burroughs Corporation, Detroit, Mich., a corporation of Michigan 5 Filed Dec. 23, 1957, Ser. No. 704,441

6 Claims. (Cl. 336-66) This invention relates to magnetic cores, and more particularly to magnetic cores provided with an external dielectric protective covering or sheath, and package assemblies thereof.

Various types of electrical apparatus, such, for example, as electronic computers, include magnetic cores having electrically conductive windings distributively applied thereto. One type of magnetic core that is utilized extensively in such structures, particularly in relatively large scale computational equipment, comprises a nonmagnetic bobbin, for example, of stainless steel or ceramic material, which has applied thereto a number of wraps of magnetizable material such as Molypermalloy. In those instances wherein the bobbin is configured to have peripheral end flanges or rims thereon, the magnetizable material is disposed on the bobbin in the area intermediate the rims or flanges. In order to obtain the desired electrical characteristics it has been found necessary to coil the magnetizable material relatively tightly and to engage the end wraps so that the wraps will not come uncoiled. Each wrap is electrically insulated from every other wrap. Techniques for accomplishing the latter results may be in accordance with the steps set forth in detail in copcnding U.S. Patent Application to Charles B. Hebeler, Serial Number 479,130, filed December 31, 1954, now Patent Number 2,925,962, entitled Magnetic Core Wrapping Apparatus, and assigned to the same assignee as the present invention.

Additionally these cores are provided with electrical toroidal windings applied thereto in any suitable manner, such as by an automatic machine of the type described and claimed in copending U.S. application to William Blackburn, S.N. 648,682, filed March 26, 1957, now Patent Number 2,973,159, entitled Machine for Winding Toroidal Cores and assigned to the same assignee as the present invention.

In order to provide the necessary dielectric properties for the magnetic core assembly, and also to provide a suitable smooth protective base or foundation for the aforementioned wire windings, it has been customary to apply to the core bobbin, as by painting, spraying, dipping or wrapping, an electrically insulating covering prior to the addition of the wire windings thereto. These techniques work very well with large size magnetic cores, however, on cores of exceedingly small size the bore diameter of the core bobbin is so small that if ordinary insulating material and techniques were utilized therewith the wire winding shuttle of the toroidal winding machine could not enter, much less pass through the bore of the core. Also, extremely small size cores increase the time consuming handling problems inherent therein.

It is an important object, therefore, of the present invention to provide a simple and inexpensive sheathed magnetic core overcoming the aforementioned problems.

It is also an important object of the present invention to provide an improved, efficient and relatively thin protective covering for magnetic cores and the like. It is a further object of the present invention to provide a relatively rigid yet pliable cheaply fabricated magnetic core jacket or sheath having a high degree of mechanical stiffness and a smoothly contoured external surface.

It is an additional object of the invention to provide a magnetic core package assembly.

in accordance with a preferred embodiment of the present invention there is provided a dielectric jacket or sheath for a non-magnetic core bobbin having peripheral end flanges and a recess therebetween. A hollow stainless steel or other non-magnetic type bobbin is provided with a plurality of wraps of magnetized material which are disposed in the recess intermediate the flanged ends thereof. The jacket comprises a pair of dielectric, substantially concentric, cylindrical members between which the bobbin is press fitted. The ends of the dielectric cylinders being joined around the flanged ends of the bobbin so as to contractually engage the flanged ends thereof. The external peripheral wall of the jacket is provided with an integral handling tab or projection which is adapted to support the core assembly during the application thereto of the electrical toroidal windings and thereafter to supportthe completed magnetic core assembly on a dielectric panel or other utilitarian structure. Preferably the jacket is molded as a unitary structure with the cylinders joined at one end and open at the other, whereby the core can be inserted between the open ends to place the core body between the two cylinders after which the open ends are sealed together.

A more complete understanding of the invention can be had from the following detailed description taken in conjunction with the appended drawings in which:

PEG. 1 is an enlarged isometric view of the preferred form of dielectric jacket embodying the present invention and showing one form of handling tab;

FIG. 2 is an enlarged isometric view similar to FIG. 1 but illustrating a completely sealed jacket housing a core and showing a modified handling tab;

FIG. 3 is atop plan view of a completed magnetic core assembly including the operating windings;

FIG. 4 is a greatly enlarged sectional view of the assembly of FIG. 3, the view being taken along the line 44 of FIG. 3, and with the handling tab broken away;

FIG. 5 is an enlarged fragmentary corner portion of a modified magnetic core assembly;

FIG. 6 is an isometric view of a portion of the core winding shuttle and the core supporting jig used therewith, and a magnetic core in winding position;

FIG. 7 is an enlarged view of a magnetic core of the present invention disposed in a portion of a notched dielectic panel;

- FIG. 8 is a side elevational view of a number of cores disposed in a groove in a portion of a dielectric panel;

FIG. 9 is a, partial sectional view along the line 9-9 of FIG. 8;

FIG. 10 is an isometric view of a dielectric panel mounting magnetic cores in accordance with the invention and having means pluggably connecting the panel to a receptacle; and,

FIG. 11 is an enlarged view of a portion of an insulating panel, showing a plurality of cores mounted thereon and the manner in which an advance winding can be interconnected or stitched therethrough.

As stated hereinabove, the present invention is particularly adapted for insulating flanged cores of the type employing one or more turns of a magnetizable wrap. However, it is to be understood that the apparatus herein described is of broader applicability and lends itself equally well to magnetic core structures or assemblies utilizing only a toroid formed of the magnetizable material. I

Referring now to FIGS. 1 through 5 which Willbe discussed simultaneously, there is shown an electrically in-.

sulating jacket or sheath 10 in the form of a double Walled sleeve of semi-rigid, resistingly yieldable structure ends (FIG. 4) of the members 12 and 14 are initially molded together, as at 18, to form a double walled, hollow container orreceptacle havingan axial bore 29 therethrough (FIG. 1), "and adapted to receive and retain a small article such as a stainless steel, ceramic or other type of nonmagnetic bobbin in the space between the walls of the cylinder.

In the fabrication of magnetic. cores generally, it is common to employ a bobbin whose overall configuration is quit'e similar to that used in sewing machines. Such a structure usually includes peripheral end flanges 22 and 24 (FIG. 4) defining an intermediate recess 26 therebetween; The end flanges ofthe bobbin may be arcuately turned or rolled over, as indicated'at 28 in FIG. 4, or the flanges may be formed substantially at right angles, as indicated at 30 in FIG 5. One or more turns or wraps of magnetizable material 32, which may be of the type capable of assuming either of two stable states of magnetic remanence, such for example as Molypermalloy, are applied to the bobbin, the wraps being electrically insulated from each other by a continuous'film 34 of suitable material, such as a mixture of magnesium oxide in oil which is applied tothe wraps during the application of the magnetizable material to the bobbin. The final turns are or may be spot welded together by means (not shown) to prevent the magnetizable material from uncoiling or slipping on the bobbin.

As can be seen from FIG. 1, the inner wall 14 of the two concentric members preferably is slightly thinner than the outer wall 12 thereof, thereby to maintain the diameter of the axial bore of the core assembly as large as possible, particularly when the overall size of the core is' exceedingly small, thus to permit the shuttle 36 (FIG. 6) of the toroidal core winding machine fr'agmentarily shown at 37, to pass therethrough during the application throughout a major portion of the'vertical dimension of the jacket wall at the time it is molded. However, inasmuch as the encapsulation of the bobbin within the insulating jacket preferably is performed by automatic machinery which utilizes heat and pressure to seal the open ends of the jacket walls, it is desirable to form the jacket so as to accept these later applied tools.

To this end, the wedge shaped tab may be undercut, as at 42. permitting the sealing and/ or encapsulating tool to be received thereover without interference. It is to be noted that the tab 40 of FIG. 1 is wedge'shaped in two dimensions; It is thicker at the top than at the bottom.

It is also narrower at'the root, i.e., at the wall of the jacket than it is at its outer end portion. This particular shape permits its'utilization in a manner and by means of apparatus to be described later on.

The wedge shaped tab 44 of the core assembly shown in FIG. 2 is wedge shaped in only one dimension and is a simpler form of the tab configuration of FIG. 1. It

of the toroidal electrical energizing windings 38 to the core assembly.

In order to produce a desired electrical output and to provide the required characteristic storage features, the

, core assemblies in the past have been supported for winding in a U-shaped clamp which gripped the insulatingly covered core at opposite rim portions thereof. This operation many times deformed the bobbins and on occasions where the operator was careless the bobbins were actually broken. To avoid such deformation and/or breakage, as well as to provide a more efficient and easier mass produced magnetic core assembly, the encapsulation technique and resulting product of this invention has successfully overcome these disadvantages. The semirigid plastic shell wholly enclosing and sealing the bobbin and 'magnetizable material therein, together with handling means to be described hereinafter, provides a desirable sub-assembly for further fabrication.

Even with the rigid, non-deformable steel bobbin, the distributed electrical windings are many times a problem to apply. For example, when part of the windings have been applied and the core is then rotated, say through 180 degrees, to expose the unwound periphery of the core bobbin to the winder shuttle, the already applied windings, when utilizing the earlier mentioned U-clamp structure, often-were subject to compressive deformation and sho'rt-circuiting or breakage due to the pressure exerted thereon by the U-clamp.

To avoid these and other problems, integrally molded has not been shown undercut because in this case the height of the jacket Wall is such as to make it unnecessary. Encapsulation of the core within the hollow confines,

of the jacket after its insertion therein is accomplished by forcing the inner and outer wall ends, shown in dotted outline in FIG. 5; toward each other over the bobbin flanges as shown in solid outline in FIG. 5. This opera tion may be performed by hand or it may be done by means of a rotating, heated mandrel (not shown), shaped to arcuately bend or roll over the two concentric wall ends laterally into abutting contact, sealing the ends to gether, as indicated at 46 in FIGSA and 5.

The wedge shaped tab 40 or 44 also is useful inprm viding means for supporting the core on an insulating panel 48, FIG. 7, in such a position that the applied wind ings 38 are not or cannot become damaged by being pressed against the supporting structure. p 7

As shown most clearly in FIG. 8, a plurality of toroidal wire wound magnetic cores 50' may have their respective wedge shaped tabs '40 or 4-4 fitted into a groove 52 of similar shape in a dielectric panel 48 so that the bores 20 of cores are in axial alignment. One or more rows may be provided, as desired. This disposition of the cores permits the conductive lead wires (not shown), to be readily available for interconnect-ion into other asso ciated electrical circuitry or to be connected to other electrical components (not shown) with which the core assemblies are to be utilized.

One important use of such magnetic cores is in a socalled shift register for electronic computational apparatus. Shift registers employ multiple magnetic core assemblies in conveniently packaged units, which in many instances are made to be pluggalbly connected into other associated electrical circuitry.

One embodiment of such a packaging ararngement ad vantageously provided by the present invention is set forth in FIG. 10. A dielectric supporting member 54 in the form of a panel or board is provided with a plurality of rows 56 and columns 58 of slots or grooves. The rows and column slots 56 and 58 are wedge shaped, with the larger portion of the Wedge configuration being disposed at the bottom of the slot, and the narrower or apex portion of the slot at the top. This construction permits the projecting tab 40 of each core 50 to matingly engage with and be positionable on the panel 54 as by sliding the tab along the groove. This structural configuration also permits the magnetic cores to be freely mounted on the top, bottom or edges of the panel, as desired, without danger of dislodgement or loss of the cores therefrom.

In order to permit the utilization of the maximum number of cores 50 at any one time on a single panel 54 a number of notches 60 may be milled, molded or otherwise formed in the edges of the panel. Since the panel assembly is to be pluggably connected to the electrical 7 circuitry used therewith, a receptacle 62 hown in broken lines, is or may be provided. One end of the panel 54 is provided with a plurality of electrical busses 64 which are adapted to interengage with electrical contacts (not shown) in the receptacle when thepanel end is introduced therein. The opposite end of the panel may be maintained free of core structures to provide handling means when engaging or disengaging the panel with the receptacle.

If desired, an aligning or orienting key 66, mating with a complementary slot 68 may be provided in the panel and the receptacle respectively to prevent the panel from being misaligned with the receptacle and to permit the equipment to be efficiently handled by an inexperienced operator having little or no training in the use of such apparatus. e

It is apparent from the foregoing that by placing a plurality of cores as in FIG. 1lenlarged to illustrate the invention-on a panel 48, making it possible to stitch the advance windings 70 through the core bores 20 of any reasonable number of coreswith the shuttle 36 of-the earlier mentioned toroidal winding machine, without having to cut or break the winding 70, as was the case with known prior art apparatus.

The single advance winding 70, as shown in FIG. 11, avoids soldered joints and the attendant difliculties therewith. Additionally, a single electrical advance winding is simple and faster to apply to the already aligned cores, and its operation is much more eflicient and less liable to failure than the soldered winding of prior art structures.

If desired a dust cover 72, shown in broken lines, doubling as an electrical shield may be employed with the final panel and receptacle assembly. In this event the cover, which may be either insulative or conductive depending on its desired end use, is or may be press fitted to the sides and end wall surfaces of the receptacle.

There has thus been described a novel, easier fabricated, magnetic core assembly utilizing a structurally semirigid dielectric sheath or jacket completely covering the inner and outer walls and the ends of the bobbin. Integral handling means on the jacket permits the application of distributed electrical windings thereto by means. of automatic high speed machinery and facilitates the mounting of the completed assembly on panels and other structures. The novel sheath provides a tough, strong, smooth and uniform foundation for the toroidal windings. In addition the sheath has excellent insulating and mechanical properties with the result that a relatively thin covering provides adequate protection to the core bobbin and its deformable magnetizable wraps.

What is claimed is: a

1. A magnetic core assembly comprising, a non-magnetic tubular bobbin having an axial bore therethrough and oppositely disposed outwardly projecting peripheral end flanges thereon providing a recess between said flanges, magnetizable material disposed in said recess, an insulating jacket enclosure for said bobbin, said enclosure comprising a pair of outer and inner substantially concentric cylindrical members, one disposed around the outside of the bobbin, and the other extending through the bore of the bobbin respectively, the ends of said cylindrical members being joined together around the flanged ends of said bobbin so that the spaces between the ends of said cylindrical members are closed, a plurality of electrical conductors disposed on said assembly in a manner projecting through said inner cylinder and around said joined ends and said outer cylinder, and a handling structure extending from said jacket, said handling structure comprising a wedge-shaped projection extending throughout a major portion of the axial length of said jacket and being undercut slightly adjacent to the jacket wall.

2. A magnetic core assembly comprising, a non-magnetic tubular bobbin having an axial bore therethrough and oppositely disposed outwardly projecting peripheral end flanges thereon providing a recess between said flanges, magnetizable material disposed in said recess, an insulating jacket enclosure for said bobbin, said enclosure comprising a pair of outer and inner substantially concentric cylindrical members, one around the outside of the bobbin, and the other extending through the bore of the bobbin respectively, the ends of said cylindrical members being joined together around the flanged ends of said bobbin so that the spaces between the ends of cylindrical members are closed, a plurality of electrical conductors disposed on said assembly'in a manner projecting through said inner cylinder and around said joined ends and said outer cylinder, and a handling structure extending from said jacket, said handling structure comprising a wedgeshaped projection, said projection being wedge-shaped in two dimensions and extending throughout a major portion of the axial length of said jacket and being provided with an undercut portion adjacent to the jacket wall.

3. A magnetic core supporting assembly comprising, an annular non-magnetic tubular bobbin having a central hub-and oppositely disposed end flanges forming a peripheral recess therebetween, magnetizable material disposed in said recess and wrapped thereon so as to tightly hug the hub of the bobbin, an electrical insulating toroidally shaped non-magnetic jacket surrounding said bobbin with portions thereof extending through the bobbin bore and around said flanges contractually engaging said flanges to tightly enclose said bobbin, a plurality of electrical conductors encircling said portions of said bobbin through said bore, a dielectric supporting structure including electrical conductive areas thereon forming electrical connecting elements, said dielectric member being provided with a matrix of rows and columns of grooves, means forming part of said jacket extending outwardly away therefrom and demountably received in the grooves of said dielectric member so as to matingly engage therein thus to secure said core and said jacket to said supporting structure, and means connecting certain of the conductors encircling said core to the connecting elements of said supporting structure.

4. A magnetic core mounting assembly comprising, a dielectric member including a plurality of electrical conductors thereon forming an electrical circuit connecting means, said dielectric member being further provided with rows and columns of slots, said slots being substantially wedge-shaped, a plurality of magnetic cores, each of said cores being provided with a dielectric jacket enclosure surrounding the same, a Wedge-shaped supporting member extending away from a portion of each of said jackets and receivable in the corresponding wedge-shaped slots of said dielectric member thus to support each core in spaced relation relative to said dielectric member, an electrical receptacle for said assembly adapted to be connected to a source of electrical energy, said electrical receptacle being engageable with said conductors on said dielectric member for completing electrical circuits through said receptacle to said source of energy, electrical conductors surrounding portions of each of said magnetic cores and being electrically interconnectible to the respective conductors of said dielectric member, alignment means in said receptacle, alignment means on said dielectric member engageable withthe alignment means on said receptacle for properly orienting said dielectric member with said receptacle, and a cover member surrounding and enclosing said dielectric member.

5. A magnetic core assembly comprising, a magnetic toroidal one-piece core bobbin having an axial bore extending therethrough, magnetizable material disposed on said bobbin a non-magnetic, non-conductive, one-piece tubular housing for said core bobbin, said housing having an inner and an outer cylindrical wall portion spaced from each other and joined together at one end in a substantially U-shaped configuration so as to form a receptacle having an axial bore therethrough, the inner cylindrical wall portion of the U-shaped walls extending through the bore of said core bobbin while the outer cylindrical wall portion surrounds the outer periphery of the core bobbin and the, upper free ends of the U-shaped walls being joined together over the core bobbin with their edges sealed together in a single circular seal thus to completely enclose and hermetically encapsulate said core bob-bin within said housing.

6. Arnagnetic core assembly, comprising, a non-magnetic tubular one-piece bobbin having an axial bore therethrough and peripheral outwardly extending flanges form ing a'recess around the outer surface of the bobbin between the flanges, inagnetizable material wrapped around said bobbin within said recess, a non-magnetic, non-conductive, cylindrical one-piece tube encircling and housingsaid wrapped bobbin, the Walls of said housing being of molded U-sharied configuration including an inner andan outer wall portion closed at one end to form a receptacle into which said bobbin is received Within the inner wall portion extending through the axial bore of the bobbin and with the outer wall portion surrounding 20 the outside of the bobbin, the upper ends ofthe wall por- 8, tions of the receptacle being curved inwardly toward each other with their edges sealed together in a single circular seal thus completely enclosing and hermetically encapsulating said wrapped bobbin within said housing, andone or more electrically conductive windings distributively toroidal-1y encircling portions of said encapsulated bobbin and passing through said bore;

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